**1. Introduction**

Cu based preparations have been used for over 200 years to control fungi and bacterial diseases in cultivated plants. Downy mildew caused by *Plasmopara viticola*, which occurs throughout the world, is one of the most destructive of all grapevine diseases. Cu-based fungicides are used to control grapevine diseases even in organic vineyards. Their use had a worldwide development after the accidental

discovery of a Bordeaux mixture in the 1880s', when the winegrowers of this region, using a mixture of Cu, sulphate and lime to avoid people to pick up and eating these grapes. Due to this practice, a French scientist called Millardet noted these covered grapes did not present a downy mildew damage. By 1885, Millardet completed experiments, that confirmed the capability of this mixture to control this disease at a relatively low cost. Therefore, the Bordeaux mixture became the first fungicide to be used on a large scale, worldwide level [1].

Cu is an essential element for plant growth occurring naturally in soils in concentrations between 5 and 30 mg kg−1, although exceptionally in soils developed on some type of basic parent material may reach values between 100 and 250 mg kg−1 [2, 3]. However, the historical use of Cu based-fungicides in vineyards leads to important increases of Cu concentrations in soils, because due to its low mobility it tends to accumulate in the upper soil layers, after rainfall removal from the vines, deposition of the senescent leaves or accidental spills [4]. Thus, in vineyard's soils in Europe is possible to find Cu concentrations higher than 100 or even 200 mg kg−1, while in subtropical areas of Brazil values higher than 1000 mg kg−1 were already found [5].

In 2018, a new publication of JRC [6] that maps Cu concentration in European Union topsoils, finds that vineyards have almost three times the average soil Cu concentration (49.26 mg/kg compared to the overall average of 16.85 mg/kg), followed by olive groves (33.49 mg/kg) and orchards (27.32 mg/kg). However, Cu distribution in the soil is strongly influenced by climate and topsoil properties. The climate will affect the number of treatments and leaching of Cu into soils, whereas soil properties have a strong influence on its behavior in this matrix [3, 4]. Once in soils, Cu is strongly complexed or sorbed by OM, oxides of Fe and Mn and clay minerals, whereas low pH values tend to promote its mobilization [3, 5].

The continuous increase of Cu concentrations in soils devoted to vineyards cause an increasing concern because high concentrations of Cu in soils may cause negative impacts on soils-organism functions and diversity, and also on vineyards surrounding ecosystems. Indeed, environmental values of Cu commonly found in soils under inputs of Cu-based fungicides are shown to be toxic not only to nontarget soil organisms like worms and microbial communities but also to aquatic organisms such as *Vibrio fischeri* and *Daphnia magna* [3]. Values ranging between 26.3 and 31.8 mg·Cu kg−1of soil, which are lower than for example the mean Cu concentration found in European vineyard soils, has been proposed to guarantee the protection of terrestrial elements and ecosystems functioning [7]. Nevertheless, when assessing the toxicity of Cu and its impacts on the environment, not only total concentrations in soils should be considered, but also its bioavailability and mobility, which are both strongly affected by the soil properties and aging processes [3]. The toxicity of Cu is also dependent on the chemical species present in soil solution (i.e. free and complexed) [3, 5]. The mobility of Cu influences its ability to migrate through the soil profile up to other environmental compartments, for example, reaching water masses more easily [3].

Due to the environmental problems related to the accumulation of Cu in soils and potential contamination of the aquatic environment, since 2007<sup>1</sup> , Cu use has been limited by European regulation, being a little controversial with principles of organic farming. Furthermore, the EU regulate by laws2 the list of approved active substances and its potential risks for protection of water and non-target organisms concerning countries to realize e.g. buffer zones to these identified risks

<sup>1</sup> Council Regulation (EC) No 834/2007 of 28 June 2007 on organic production and labelling of organic products.

<sup>2</sup> REGULATION (EU) No 540/2011. https://eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=CELE X:32011R0540&from=EN.

#### *Alternatives to CU Applications in Viticulture: How R&D Projects Can Provide Applied… DOI: http://dx.doi.org/10.5772/intechopen.100500*

and risk mitigation measures where appropriate. In the past, regular inputs of Cu up to 30 kg·ha−1 (per every 5 years) were frequently attained and allowed. After each application, the residue is typically accumulated in the upper 15 cm of soil, given the high affinity of Cu with the soil organic matter (SOM), that contains several reactive groups, like carboxylic and phenolic groups, which can complex Cu cations, after deprotonation, reducing its mobility in soils [8].

Not only in Europe, in California, but there were also some studies which have shown that there was an increase in the use of Cu in vineyards, caused an accumulation in soils from 6 to 9 kg·ha−1 [9] during the last years of the 90s'.

Nowadays, and after recognizing the risks of copper accumulation in soils, the use of Cu in the European vineyard is limited to a maximum of 28 kg Cu·ha−1 and over 7 years3 . This limit is usually applied to organic farming, whilst for conventional viticulture, there are alternative plant protection products available resulting in much lower Cu quantities. Some countries e.g. Germany and Austria had more strict limits (3 kg·yr.−1·ha−1) when necessary. Private organic organizations, like. Biodynamic growers with Demeter certification4 and other biodynamic groups as ECOVIN, Bioland, Natruland, Bio-Austria, etc. can only use a maximum of 3 kg·yr.−1·ha−1. In France, the national legally allowed application rate of Cu is 6 kg·yr.−1·ha−1 with flexible mechanisms (30 kg·yr.−1·ha−1) for organic agriculture. Furthermore, the France Minister of Agriculture and Food launched a national program "Ecophyto5 " aimed at reducing the use of pesticides in agriculture.

Other standards like Slovenian or the Australian and New Zealand guidelines, focus on risk assessment of contaminated sites and give support decisions about remediation measures. In general, where total Cu concentrations in soil exceeding 60 mg·kg−1, sites require environmental investigations [10, 11].

Despite the efforts for reducing the use of copper, the situation is challenging for organic agriculture for which synthetic active substances cannot be part of the solution.
